A variety of methods are known for creating oscillator circuits for providing periodic signals of a desired frequency. A large class of oscillator configurations that exist in monolithic integrated circuit design are those known as relaxation oscillators or multivibrators. Conventional relaxation oscillators operate by alternately charging and discharging a timing capacitor between two internally set threshold voltage levels. This results in the generation of a periodic output signal waveform whose frequency is inversely proportional to the value of the timing capacitor. Conventional relaxation oscillator configurations include R-C charge and discharge oscillators, constant-current charge and discharge oscillators, and emitter-coupled multivibrators.
However, conventional relaxation oscillators suffer from a number of limitations that affect both their implementation and the quality of the resulting periodic output signal waveform. For example, in conventional relaxation oscillators comparator delay contributes significantly to the oscillator period of the relaxation oscillator. In order to increase precision, the comparator must be made to operate very quickly. This usually has the side effect of increased supply current requirements and compromised accuracy at high speeds of operation. Thus there is a need for a precision relaxation oscillator having improved implementation properties, as well as an improved periodic output signal waveform.